Recent evidence demonstrates medication non-adherence rates as high as 74% in ankylosing spondylitis (AS), 90% in gout, 50% in psoriatic arthritis (PsA), 75% in systemic lupus erythematosus (SLE), and 82% in rheumatoid arthritis (RA). The effects of socioeconomic factors have been studied most in RA and SLE but with inconsistent findings. Nonetheless, the evidence points to having prescription coverage and costs of treatment as important factors in RA and education as an important factor in SLE. Limited data in AS and gout, and no studies of the effects of socioeconomic factors in PsA, show knowledge gaps for future research. Finally, there is a dearth of data with respect to the impacts of non-adherence on economic outcomes.